Telescoping suspension fork having a quick release wheel axle clamp

ABSTRACT

A telescoping fork for the front wheel of a two wheel vehicle comprises a pair of outer tubes that each have a bottom end and a top end. An upper structural member and a lower structural member connect the outer tubes. Further, each outer tube tapers outwardly, both externally and internally, in a direction from the bottom end toward the lower structural member and from the top end toward the lower structural member. The structural members may attach to a top and bottom of a steering column.

BACKGROUND OF THE INVENTION

[0001] This invention relates generally to the field of two wheelvehicles. More specifically, the invention relates to two wheeledvehicle suspension systems and releasable wheel clamping systems.

[0002] The use of front and full suspensions in two wheeled vehicles hasbecome widespread. For example, motorcycles have long had suspensionsystems. In recent years, front and full suspension systems in mountainbikes have become almost standard equipment. One pioneering effort tocreate such suspension systems was spearheaded by Rockshox, Inc. asdescribed generally in U.S. Pat. Nos. 4,971,344; 5,186,481; 5,456,480;and 5,580,075, the complete disclosures of which are herein incorporatedby reference. Another successful suspension system for a two wheeledvehicle is described in copending U.S. application Ser. Nos. 09/502,272and 09/502,746, both filed Feb. 11, 2000, the complete disclosures ofwhich are herein incorporated by reference.

[0003] This invention provides another type of suspension for twowheeled vehicles. The invention also relates to the releasable couplingof a wheel to the fork of a two wheeled vehicle.

SUMMARY OF THE INVENTION

[0004] In one embodiment, the invention provides a telescoping fork forthe front wheel of a two wheeled vehicle. The fork comprises a pair ofouter tubes that each have a top end and a bottom end. An upperstructural member and a lower structural member are employed to connectthe outer tubes, with the lower structural member being spaced below theupper structural member. Further, each outer tube tapers outwardly, bothexternally and internally, in a direction both from the top end and thebottom end toward the lower structural member. With such aconfiguration, the strength of the outer tubes is increased withoutsignificantly increasing the weight of the fork.

[0005] In one aspect, the lower structural member is welded to the outertubes, and steering bearings are coupled between the upper structuralmember and the lower structural member. With this configuration, thesteering bearings may be used to attach the fork to a vehicle frame. Inanother aspect, the lower structural member may have a hollow boxsectional shape.

[0006] In one particular arrangement, the fork further includes a pairof inner tubes that are disposed to slide within the pair of outertubes. The inner tubes each have a bottom end and a top end, and thebottom ends of the inner tubes extend out of the bottom ends of theouter tubes. In one option, a single bushing may be disposed betweeneach outer tube and each inner tube. The bushings may be located at thebottom ends of the outer tubes and have a length that is longer than adiameter of the inner tube. The use of such a bushing helps maintain anoil layer between the bushing and the inner tube.

[0007] In another particular aspect, the fork may include a bracketdisposed at the bottom end of each inner tube. The brackets are employedto clamp a front wheel axle to the inner tubes. Optionally, at least oneof the brackets may have a mount for receiving a disk brake caliper.

[0008] Another feature of the fork is the use of a handle bar clampingdevice that is coupled to the upper structural member. In this way, ahandle bar may be coupled to the fork.

[0009] One particular embodiment of the invention is an adjustable fluiddamping system. The fluid damping system may comprise a damper tubeextending upward from the top end of the inner tube (and in some casesthe damper tube may simply be an extension of the inner tube), a hollowdamper rod coupled to the top end of the outer tube and extending intothe damper tube, and a damper piston valve coupled to the damper rodthat seals against the damper tube. The fluid clamping system mayfurther include a lock tube that is disposed within the damper rod. Thedamper rod may have at least one upper orifice and one lower orifice,and the lock tube may be rotatable from the top end of the outer tube toclose the lower orifice to limit the amount of extension of the lowertube out of the upper tube. In this way, the amount of extension of thesuspension system may easily be adjusted from outside of the fluiddamping system. For instance, when ready to climb a steep hill, therider may quickly adjust the lock tube by turning a knob to limit theamount of extension during climbing.

[0010] In one particular aspect, this is accomplished by configuring thedamper piston valve as a one-way valve that permits fluid flow in anupward direction upon compression of the inner tube into the outer tube.Further, a sleeve may be disposed over a top portion of the damper rodand the lock tube. The sleeve is configured to close the upper orificeas the upper tube extends relative to the lower tube, such that furtherextension is prevented if the lower orifice is closed by the lock tube.Conveniently, a stop may be positioned between the top of the outer tubeand the top of the inner tube to stop compression of the inner tube intothe outer tube.

[0011] In one alternative aspect, the inner tube may have a closed endor section, and a sealed piston may be disposed inside the inner tube.The piston may be connected to a rod that extends and attaches to thetop end of the outer tube. Further, a gas may be held within the innertube and is compressed by the piston to provide a damping effect.Optionally, a spring may be disposed between the bottom end of the innertube and the piston to form a biasing effect. The rod may also be hollowto permit the gas pressure in the inner tube to be adjusted by a valveat the top end of the outer tube.

[0012] In a further embodiment, the invention provides a releasableclamp system for clamping a wheel axle of wheel to a two-wheeledvehicle. The clamp system comprises a frame member that defines a shapethat is configured to receive a portion of the wheel axle. A cover plateis privotally attached to the frame member and is configured to receiveanother portion of the wheel axle. In this way, the cover plate may bemoved to a closed position where the frame member and the cover plategenerally encompass and clamp the wheel axle, and to an open positionwhere the wheel axle may be removed. A lever is pivotally attached tothe cover plate, and a hook member is pivotally attached to the lever.The hook member is configured to hook onto the frame member and bepulled by the lever to secure the cover plate to the frame member whenthe cover plate is moved to the closed position.

[0013] In one aspect, the cover plate may be pivotally attached to a topend of the frame member to permit the wheel axle to be verticallyreleased from the frame member. In another aspect, the inner surfaces ofthe frame member and the cover plate that are adjacent the wheel axleare each semi-circular in geometry.

[0014] In a further aspect, the hook member may be T-shaped, and theframe member may include a shoulder with a slot into which the hookmember is received. Optionally, the hook member may be constructed oftwo pieces that are threadably connected together. In this way, theclamping force on the wheel axle may be adjusted by rotating the piecesrelative to each other prior to clamping.

[0015] In yet another aspect, torsion springs may be provided at pivotpoints located where the cover plate attaches to the frame member andwhere the lever attaches to the cover plate. The torsion springs holdthe cover plate open when not clamping the wheel axle. Further, a mountmay be provided on the frame member to mount a disk brake caliper to theframe member.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016]FIG. 1 is a front isometric view of a telescoping fork releasablycoupled to a front wheel of a two wheeled vehicle according to theinvention.

[0017]FIG. 2 is a more detailed view of a top portion of the fork ofFIG. 1.

[0018]FIG. 3 is a rear isometric view of the fork of FIG. 1 showncoupled to a handle bar.

[0019]FIG. 4 is a cross-sectional top view of the fork of FIG. 1 takenthrough a lower structural member.

[0020]FIG. 5 is a cross-sectional side view of the fork of FIG. 1

[0021]FIG. 6 is a more detailed view of some of the components of thefork of FIG. 5 showing fluid flow during compression.

[0022]FIG. 7 illustrates the components of FIG. 6 showing fluid flowduring extension.

[0023]FIG. 8 is a more detailed view of a bushing disposed between anouter tube and an inner tube.

[0024]FIG. 9 is a more detailed view of a clamp system of the fork ofFIG. 1.

[0025]FIG. 10 illustrates the clamp system of FIG. 9 in an openposition.

[0026]FIG. 11 is another view of the clamp system of FIG. 10.

[0027]FIG. 12 is a cross sectional side view of the clamp system of FIG.9.

[0028]FIG. 13 is a cross-sectional side view of an alternative forksection according to the invention.

[0029]FIG. 14 is a cross-sectional side view of a further embodiment ofa fork section according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0030] In one aspect, the invention provides various suspension systemshaving a variety of features. One such feature is the use of fork thatis constructed of telescoping outer tubes. The tubes have an innerdiameter and an outer diameter that both increases in a direction fromthe axle mount upward as well as from the top of the fork downward. Themaximum amount of taper may occur near where the two tubes are joinedtogether by a structural member. For example, the tubes may taperoutward from an inner diameter in the range from about 32 mm to about 34mm and an outer diameter in the range from about 34 mm to about 38 mm,to an inner diameter in the range from about 44 mm to about 48 mm and anouter diameter in the range from about 48 mm to about 52 mm, althoughother dimensions are possible. Such a configuration increases thestrength of the fork without appreciably increasing its weight.

[0031] Another feature of the invention is the ability to limit theamount of extension of the suspension system. This may be done manuallyfrom outside of the suspension system. For example, such an adjustmentmay be done by simply turning a knob. Such a feature is useful whenpeddling uphill to keep the front end of the bicycle closer to theground to prevent tipping backward. When on level or down slopingterrain, the suspension system may again be adjusted to permit fullextension.

[0032] A further feature is a releasable clamp system that provides fora quick release of the wheel from the fork. By the simple operation of alever, the wheel may be vertically released from the fork.

[0033] Referring now to FIG. 1, one embodiment of a fork 10 of atwo-wheeled vehicle will be described. Fork 10 is constructed of a pairof outer tubes 12 and 14 that may both be fashioned in a substantiallysimilar manner. Outer tubes 12 and 14 are coupled together by a lowerstructural member 16 and an upper structural member 18. Outer tubes 12and 14 may be constructed of a strong and rigid material, such as steel,aluminum, or the like. Lower structural member 16 may be constructed ofa similar material and may be welded to outer tubes 12 and 14. Upperstructural member 18 may be coupled to tubes 12 and 14 using screws 20(see also FIG. 2) that may be tightened or loosened using an allenwrench. Alternatively, upper structural member 18 may be welded to tubes12 and 14. Upper structural member 18 also includes a couplingarrangement 22 for coupling a handlebar 24 (see FIG. 3) to fork 10.Optionally, this may be incorporated directly into upper structuralmember 18.

[0034] Coupled between structural members 16 and 18 is a rotatablemember 26 having steering bearings. Rotatable member 26 is a steeringcolumn that is configured to be coupled to a vehicle frame as is knownin the art to complete the vehicle.

[0035] Extending out of outer tubes 12 and 14 are inner tubes 28 and 30.Inner tubes 28 and 30 are slidable within outer tubes 12 and 14 and arecoupled to a clamping system 34, 36 as described hereinafter. As alsodescribed hereinafter, an adjustment knob 78 is at a top end of outertube 12 and may be used to adjust the amount of extension of inner tubes28 and 30 out of outer tubes 12 and 14.

[0036] Coupled to inner tubes 28 and 30 are clamp systems 34 and 36 thatare each substantially identical. Clamp systems 34 and 36 are employedto couple an axle 38 of a wheel 40 to fork 10 and will be described ingreater detail hereinafter.

[0037] Lower structural member 16 is shown in cross section in FIG. 4and has a box sectional shape. Such a shape is useful in that itprovides the greatest amount of rigidity for the least weight.

[0038] As best shown in FIG. 5, outer tube 12 (as well as outer tube 14)tapers outward, both externally and internally, from near its bottom end42 to a location 44 where tube 12 is coupled to lower structural member16 (see FIG. 1). Outer tube 12 also tapers outward, both externally andinternally from its top end to location 44. This configuration permitsouter tube 12 to have an inner diameter at bottom end 42 that isslightly larger than inner tube 28, and to have a greater inner diameterat location 44 where greater stresses occur. In this way, the overallstrength of fork 10 is increased. Further, by also increasing the outerdiameter of tube 12, a relatively small wall thickness may be maintainedto reduce the weight of fork 10.

[0039] Referring to FIGS. 5-7, construction and operation of a dampingsystem 50 will be described. Damping system 50 is constructed out ofouter tube 12 and inner tube 28 that slides within outer tube 12. Innertube 28 is coupled to a damper tube 52 that has threads 54 that threadinto corresponding threads of inner tube 28. Damper tube 52 has a closedbottom end 56 and a top end having a seal head 58. In some cases, dampertube 52 may simply be an integrally formed extension of inner tube 28.Extending down from seal head 58 and into damper tube 52 is an outersleeve 60. An O-ring 62 is coupled to the bottom end of outer sleeve 60.Extending through outer sleeve 60 and seal head 58 is a hollow damperrod 64. An O-ring 65 provides a seal between seal head 58 and damper rod64. Coupled to a bottom end of damper rod 64 by a nut 63 is a dampervalve piston 66 that is configured as a one-way valve. Piston valve 66also divides damper tube 52 into a lower oil chamber 68 and an upper oilchamber 70, although other fluids may be used as well. Piston valve 66includes a flexible valve washer 71 that is shown in an open position inFIG. 6 during compression of damping system 50 to permit fluid flowthrough a valve 72. As shown in FIG. 7, washer 71 is an a closedposition during extension of damping system 50 to prevent flow throughorifice 72. Disposed above piston valve 66 is a bottom extension orifice74 (although more than one may be used). Also, positioned above bottomorifice 74 is one or more top extension orifices 75.

[0040] Coupled to a top end of damper tube 64 is a top cap 76 that inturn is coupled to outer tube 12 (see FIG. 5). A bottom out pad 79 iscoupled to top cap 76 and may comprise an O-ring. Pad 79 is used tosoften the impact and protect top cap 76 if damping system 50 bottomsout, i.e., when seal head 58 reaches top cap 76. Optionally, pad 79 maybe provided anywhere along damper rod 64, and damper rod 64 may beprovided with a shoulder to hold pad 79 in place. Disposed on top of topcap 76 is an adjuster knob 78 that in turn is coupled to a lock tube 80.In turn, lock tube 80 is adjacent to and coaxially disposed withindamper rod 64. Knob 78 is rotatable to rotate lock tube within damperrod 64. Lock tube 80 also includes a set of upper orifices 82 that arealigned with top orifices 75 of damper rod 64. Orifices are preferablyconfigured as slots so that when knob 78 is rotated, a fluid flow pathremains through damper rod 64 and lock tube 80.

[0041] Lock tube 80 also includes a lower orifice 84 that is alignedwith bottom extension orifice 74 of damper rod 64. Upon rotation of knob78, orifice 84 may be rotated out of alignment with orifice 74 so thatfluid flow between upper oil chamber 70 and the interior of damper rod64 through orifice 74 is prevented when orifice 75 passes above O-ring62. Damper rod 64 also includes an opening 86 at its bottom end thatpermits fluid to flow both into and out of damper rod 64.

[0042] By utilizing lock tube 80, damper system 50 may be operated inone of two modes simply by rotating knob 78. In FIGS. 6 and 7, dampersystem 50 is shown in an unrestricted mode where orifice 84 is alignedwith orifice 74. In FIG. 6, damper system 50 is being compressed, suchas when a rider encounters a bump. In such cases, inner tube 28 slidesinto outer tube 12. Since damper tube 52 is coupled to inner tube 28 andtop cap 76 is coupled to outer tube 12, damper rod 64 and lock tube 80move further into damper tube 52. In so doing, the fluid within lowerchamber 68 moves upwardly through valve orifice 72 and into upperchamber 70, as well as upwardly through damper rod 64 as shown by theflow lines in FIG. 6. The fluid flowing upward through damper rod 64 mayexit into upper chamber 70 through orifices 74 or 75 as shown. The“stiffness” of damping system 50 during compression may be varied byvarying the flexibility of valve washer 71, as well as the number and/orsize of the exit orifices.

[0043] During extension (as shown in FIG. 7), valve washer 71 is forceddownward to close orifice 72. As such, fluid in upper chamber 70 mayonly pass into lower chamber 68 through damper rod 64 as shown by theflow lines. If the amount of extension becomes so great that orifices 75move within outer sleeve 60, fluid in upper chamber 70 may still passinto lower chamber 68 through orifices 74 and 84.

[0044] Damper system 50 may be placed into an extension limiting mode bysimply turning knob 78 until orifice 84 is out of alignment with orifice74. In this configuration, lock tube 80 prevents fluid flow throughorifice 74 and into damper rod 64. Hence, once damper system 50 extendssufficient to move orifice 75 beyond O-ring 62, outer sleeve 60 preventsfluid flow from upper chamber 70 and into damper rod 64 via orifice 75.Moreover, because orifice 74 also is closed, none of the fluid in upperchamber 70 may pass into lower chamber 68 is prevented, thus stoppingfurther extension.

[0045] Hence, a rider may quickly and easily control the amount ofextension simply by rotating knob 78 which is easily accessible since itis outside of outer tube 12. For example, when climbing a hill a ridermay want to keep the front end of the bicycle closer to the ground. Todo so, knob 78 may simply be turned to limit the amount of extension.When at the top of the hill, knob 78 may be moved back to place dampingsystem 50 in normal operation. As will be appreciated, the amount ofextension may also be controlled by the number, size and/or location oforifices 75. For example, by moving orifices downward, more extensionmay be achieved.

[0046]FIG. 8 illustrates the slidable connection between inner tube 28and outer tube 12. For convenience of illustration, damper system 50 hasbeen removed. Coupled to outer tube 12 is a bushing 90 that is held inplace by a sheath member 92. Also coupled to sheath member 92 is a sealor dust wiper 94 that helps prevent dirt and other particulate frompassing between inner tube 28 and outer tube 12. Bushing 90 isconfigured to maintain a layer of oil between itself and inner tube 28during compression and expansion This is accomplished by using only asingle bushing so that edges do not exist between multiple bushings.Further, bushing 90 has a length that is longer than the diameter ofinner tube 28. This length also helps to maintain the oil layer.

[0047] Referring now to FIGS. 9-12, clamp systems 34 and 36 will bedescribed in greater detail. Clamp systems 34 and 36 are constructed ofidentical components and will each be described using the same referencenumerals. Clamp system 34 is constructed of a frame member 100 that iscoupled to inner tube 28. Frame member 100 has an inner surface 102 forreceiving wheel axle 38 and may be approximately semi-circular in shape,although other shapes are possible. Pivotally attached to frame member100 by a pivot pin 104 is a cover plate 106 that also has an innersurface 108 for receiving the other half of wheel axle 38. As such,inner surface 108 may also be approximately semi-circular. Pivotallycoupled to cover plate 106 by a pivot pin 110 is a lever 112, andpivotally coupled to lever 112 by a pivot pin 114 is a hook member 116.Hook member 116 is constructed of a housing 118 and a hook 120 that isT-shaped. Hook 120 is threadably connected to housing 118 to permit thedistance between hook 120 and lever 112 to be adjusted.

[0048] Frame member 100 includes a shoulder 122 having a slot 124 forreceiving hook 120 when clamping wheel axle 38 to frame member 100. Inuse, wheel 40 (see FIG. 1) may be coupled to inner tube 28 by placingclamp system 34 in an open position as shown in FIGS. 10 and 11.Although not shown, torsion springs may be provided about pivot pins 104and 110 to hold clamp system 34 in the open position. Wheel axle 38 maythen be moved vertically up and placed adjacent inner surface 102. Thisis made possible by locating cover plate 106 at the top end of innersurface 102. Lever 112 may then be operated to pivot cover plate 106about the other half of wheel axle 38 and to place hook 120 into slot124 so that the end of hook is beyond shoulder 122. Lever 112 is thenrotated until pivot pin 114 moves to an over center position (i.e., pasta line passing between pin 110 and hook 120) and locks cover plate 106in place where wheel axle 38 is clamped in place by surfaces 102 and 108as shown in FIG. 12. To adjust the clamping force, hook 120 may bescrewed further into or out of housing 118. When ready to remove wheel40, lever 112 is simply pulled and hook 120 is removed from slot 124. Asimilar process is used to operate clamp system 36.

[0049] Also coupled to frame member 100 is a mount 128 that may beemployed to mount a disc brake caliper to clamp system 34. Such a discbrake caliper may be similar to those known in the art, e.g., as definedby the G-3 Shimano disc brake standard.

[0050] Fork 10 may be modified to include other types of dampingsystems. Two such examples are illustrated in FIGS. 13 and 14. Forconvenience of discussion, the elements in FIGS. 13 and 14 that aresimilar to those described in connection with fork 10 will be describedusing the same reference numerals. FIG. 13 illustrates a fork section200 that is constructed of an outer tube 12 that may be connected to theouter tube of another fork section. For example, a fork may beconstructed of fork section 200 that is coupled to the outer tube 12 ofa fork section 204 (see FIG. 14) in a manner similar to the embodimentillustrated in FIG. 1. Outer tubes 12 may taper outwardly in a mannersimilar to that previously described.

[0051] Slidable within outer tube 12 is inner tube 28 (that is coupledto damper tube 52). In some cases, inner tube 28 and damper tube 52 maybe the same tube. Damper tube 52 includes a closed end 206, and a sealedpiston 208 is slidable within tube 52. A hollow rod 210 is connected topiston 208 at its bottom end and is coupled to the top of outer tube 12at its top end. The top end of outer tube 12 includes a valve region 212into which a valve may be disposed. This valve permits the gas pressurein the space between piston 208 and closed end 206 to be adjusted.

[0052] Hence, fork section 200 functions as a damper to dampen a shockexperienced by the two wheeled vehicle. More specifically, as inner tube28 slides into outer tube 12, the gas in damper tube 52 is compressed toprovide a damping effect.

[0053] Fork section 204 of FIG. 14 is essentially identical to that offork section 200 but includes a spring 216 that provides a biasingeffect. Hence, fork section 204 may be used in combination with forksection 200 to provide a fork having both a damping and biasing effect.More specifically, after the fork experiences a shock and is compressed,spring 216 forces inner tube 28 out of outer tube 14

[0054] The invention has now been described in detail for purposes ofclarity and understanding. However, it will be appreciated that certainchanges and modifications may be practiced within the scope of theappended claims.

What is claimed is:
 1. A telescoping fork for the front wheel of a twowheeled vehicle, the fork comprising: a pair of outer tubes that eachhave a top end and a bottom end; an upper structural member connectingthe outer tubes; and a lower structural member connecting the outertubes, wherein the lower structural member is spaced below the upperstructural member, wherein the upper structural member and the lowerstructural member are configured to be connected to a steeringmechanism; wherein each outer tube tapers outwardly, both externally andinternally, in a direction from the bottom end toward the lowerstructural member and from the top end toward the lower structuralmember.
 2. A fork as in claim 1, wherein the lower structural member hasa hollow box sectional shape.
 3. A fork as in claim 1, furthercomprising a pair of inner tubes disposed to slide within the pair ofouter tubes, wherein the inner tubes each have a bottom end and a topend, and wherein the bottom ends of the inner tubes extend out of thebottom ends of the outer tubes and are configured to connect to a wheelaxle.
 4. A fork as in claim 3, further comprising a single bushingdisposed between each outer tube and each inner tube, wherein thebushings are located at the bottom ends of the outer tubes, and whereinthe bushings have a length that is longer than a diameter of the innertube.
 5. A fork as in claim 3, further comprising a bracket disposed atthe bottom end of each inner tube, wherein the brackets are adapted toclamp a front wheel axle to the inner tubes.
 6. A fork as in claim 5,wherein at least one of the brackets has a mount for receiving a diskbrake caliper.
 7. A fork as in claim 1, further comprising a handle barclamping device coupled to the upper structural member.
 8. A fork as inclaim 1, wherein the upper structural member incorporates a handle barclamping device.
 9. A fork as in claim 3, further comprising a fluiddamping system disposed within at least one of the inner tubes.
 10. Afork as in claim 9, wherein the fluid damping system comprises a hollowdamper rod coupled to the top end of the outer tube and extending intothe inner tube, a sealing member disposed to create a seal between theinner tube and the damper rod near the top end of the inner tube; and adamper piston valve coupled to the damper rod that seals against theinner tube.
 11. A fork as in claim 10, wherein the fluid damping systemfurther comprises a lock tube disposed within the damper rod, whereinthe damper rod has at least one upper orifice and one lower orifice, andwherein the lock tube is rotatable from the top end of the outer tube toclose the lower orifice, and further comprising a sleeve disposed over atop portion of the damper rod and the lock tube, wherein the sleeve isconfigured to close the upper orifice as the upper tube extends relativeto the lower tube, such that further extension is prevented if the lowerorifice is closed by the lock tube.
 12. A fork as in claim 11, whereinthe damper piston valve is a one-way valve that permits fluid flow in anupward direction upon compression of the inner tube into the outer tube.13. A fork as in claim 3, wherein at least one of the inner tubes has aclosed end, and further comprising a sealed piston inside the inner tubethat is connected to a rod that extends and attaches to the top end ofthe outer tube, and a gas within the inner tube that is compressed bythe piston to provide a biasing effect.
 14. A fork as in claim 13,further comprising a spring disposed between the bottom end of the innertube and the piston to provide a biasing effect.
 15. A fork as in claim13, wherein the rod is hollow to permit the gas pressure in the innertube to be adjusted by a valve at the top end of the outer tube.
 16. Afork as in claim 10, further comprising a stop positioned between thetop of the outer tube and the top of the inner tube to stop compressionof the inner tube into the outer tube.
 17. A fluid damping system,comprising: a tube member having a closed end and an open end; a hollowdamper rod extending through the open end of the tube member; a damperpiston valve coupled to the damper rod and movable within the tubemember, wherein the damper piston valve comprises a one-way valve thatpermits fluid flow in an upward direction upon compression; a sealingmember disposed to create a seal between the tube member and the damperrod near the top end of the tube member; a sleeve disposed over a topportion of the damper rod; wherein the damper rod includes at least anupper orifice and a lower orifice that are located between the sealingmember and the piston valve to permit fluid flow past the piston valveby passing through the damper rod during extension of the damper rod outof the tube member, wherein the lower orifice is manually closable, andwherein the sleeve is configured to close the upper orifice uponextension such that further extension is limited if the lower orifice isclosed.
 18. A system as in claim 17, further comprising a lock tubedisposed within the damper rod, and wherein the lock tube is manuallyrotatable externally of the tube member to close the lower orifice tolimit the amount of extension.
 19. A system as in claim 18, wherein thesleeve comprises an extension of the sealing member.
 20. A releasableclamp system for clamping a wheel axle of a wheel to a two wheeledvehicle, comprising: a frame member defining a shape that is adapted toreceive a portion of the wheel axle; a cover plate pivotally attached tothe frame member that is adapted to receive another portion of the wheelaxle, wherein the cover plate is movable between a closed position wherethe frame member and the cover plate generally encompass and clamp thewheel axle, and an open position that permits removal of the wheel axle;a lever pivotally attached to the cover plate; and a hook memberpivotally attached to the lever, where the hook member is configured tohook onto the frame member and be pulled by the lever to secure thecover plate to the frame member when the cover plate is moved to theclosed position.
 21. A clamp system as in claim 20, wherein the coverplate is pivotally attached to the top of the frame member to permit thewheel axle to be vertically released downward from the frame member. 22.A clamp system as in claim 20, wherein the frame member and the coverplate each have inner surfaces that are adjacent to the wheel axle whenthe cover plate is in the closed position, and wherein the innersurfaces and the wheel axle are each semicircular in geometry.
 23. Aclamp system as in claim 20, wherein the hook member is T shaped ingeometry, and wherein the frame member includes a shoulder with a slotinto which the hook member is receivable.
 24. A clamp system as in claim23, wherein the hook member comprises two pieces that are threadablyconnected together such that the clamping force applied to the wheelaxle is adjustable by rotating the two pieces relative to each other.25. A clamp system as in claim 20, wherein the cover plate is pivotallyattached to the frame member at a pivot point, wherein the lever ispivotally attached to the cover plate at a pivot point, and furthercomprising torsion springs at each of the pivot points to hold the coverplate in the open position when not clamping the wheel axle.
 26. A clampsystem as in claim 20, further comprising a mount on the frame memberthat is adapted to mount a disk brake caliper to the frame member.